1. Field of the Invention
The present invention relates to a buckle pretensioner system which, when a vehicle disposed with the buckle pretensioner system undergoes a sudden deceleration, pulls, in a vehicle occupant restraining direction of a webbing belt for restraining a vehicle occupant, a buckle that engages with a tongue plate inserted through an intermediate portion of the webbing belt.
2. Description of the Related Art
In a seat belt device, a tongue plate inserted through an intermediate portion of a webbing belt is inserted into and engages with a buckle, whereby the body of a seated vehicle occupant is restrained by the webbing belt.
There are also seat belt devices disposed with a pretensioner system that improves the restraint of the vehicle occupant by pulling back, by a predetermined amount per buckle, the webbing belt worn by the vehicle occupant when the vehicle undergoes a sudden deceleration. Examples thereof are disclosed in Japanese Patent Application Laid-Open Publication (JP-A) Nos. 5-254395 and 8-40205.
In a vehicle disposed with a back seat, there are many instances where the vehicle occupant is seated in various postures. For this reason, even if the vehicle occupant is wearing the webbing belt, sometimes the webbing belt does not catch on the proper position of the vehicle occupant, such as the lumbar region. If the vehicle suddenly decelerates and the pretensioner system is actuated in this state, a large load ends up being applied to the vehicle occupant from the webbing belt.
Various countermeasures have been devised to address this problem, such as reducing the reclinable angle of the seat so that an excessive reclining angle cannot be set, and increasing the hardness of the front part of the seat cushion to make it difficult for the lumbar region of the vehicle occupant to slide forward from the proper position in the seat.
However, in systems where such countermeasures have been administered, there has been the drawback that the comfort is reduced when the vehicle occupant is seated in the seat.